“I’ve been thinking about this over the past year or so. [And I] keep meeting really smart people, and the situation keeps seeming to get more dire. This isn’t anyone’s plan A, but we seem to totally be failing at curbing emissions fast enough,” wrote Y Combinator partner Sam Altman, in an email. “If one talented group of people decided to take this seriously and work on one of these ideas, I’d be delighted. We have good luck with RFS’s that sound extremely ambitious in the past. I believe you have to set out very ambitious goals, and think about what’s at the edge of possible, in order to get significant breakthroughs to happen.”

Limiting the damage caused by climate change, global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45% from 2010 levels by 2030, reaching ‘net zero’ around 2050 — meaning that any remaining emissions would need to be balanced by removing CO2 from the air. No government is anywhere near achieving this goal and certainly not the world’s most populous and most polluting nations — including the U.S., India, and China.

As the Y Combinator statement announcing the new initiative itself suggests, the world is well past reversing climate change by simply reducing emissions.

“Phase 1” of climate change is reversible by reducing emissions, but we are no longer in “Phase 1.” We’re now in “Phase 2” and stopping climate change requires both emission reduction and removing CO2 from the atmosphere. “Phase 2” is occurring faster and hotter than we thought. If we don’t act soon, we’ll end up in “Phase 3” and be too late for both of these strategies to work.

Some iterations of Y Combinator’s plan for carbon sequestration already exist or have been tried by previous startups. In its blog post, the accelerator pointed to bio-energy with carbon capture and storage, which would require growing new biomass to convert into energy and then capturing the emissions created when that biomass is burned for power and burying it in the ground. Other methods that have been floated include direct air capture; a technology used by companies like Carbon Engineering — a Bill Gates-backed company that takes carbon dioxide from the air and converts it into fuels and chemicals; LanzaTech, a New Zealand company that converts carbon into chemicals and fuels; and the Australian cement manufacturer Calix.

Further afield is solar radiation management, which would reflect inbound sunlight back into space. Researchers have proposed sending satellites into space that would reflect solar energy, injecting sulfate aerosols into the stratosphere, cloud-seeding to make them more reflective, or whitening roofs and developing reflective crops that would not absorb as much sun.

Those technologies are (to some degree) here already, what Y Combinator is asking for from startups and entrepreneurs are the next generation of geo-engineering technologies.

This new initiative from Y Combinator is both the ultimate expression of Silicon Valley hubris and a clear-eyed attempt to wrestle with what is quickly becoming accepted as the reality of climate change and its impact on the world.

And fortunately or unfortunately for everyone, without the support of the word’s governments, none of these solutions, however viable or compelling will ever see the light of day. What’s equally troubling is the thought that some government, recognizing how dire the situation is, might go rogue and unilaterally implement some of these technologies without regard to the consequences of the global ecosystem.

If the apocryphal butterfly flapping its wings could create monsoons halfway around the world, what might the potential implications be of creating new life in the ocean to absorb global emissions?

Altman acknowledges that the best solution is still emissions reduction — and he’s invested in nuclear power companies that could be a part of that solution — but the growing consensus is that emissions reduction may no longer be enough (unless a moonshot discovery is made).

That leaves building a world that’s better able to adapt to the consequences or changing the world to the solve the problem.